Screening Of High Tield Protease Producing Strains And Research On Enzyme Characterization

From the soil of the greenhouses, the raising dairy factories, the raising chicken factories, the raising pig factories, soybean processing plants, sludge of fish pond, the soil buried dead fish and the soil dumped okara where surrounding suburb of Xinxiang City contain higher protein, we gathered a strain produced protease named N1.Researched on enzyme characterization, the results showed that the optimum temperature of this protease was 60℃, optimum pH 8, at pH 6 also had high activity. The activity at pH 6 was 1020U/ml, at pH 8 was1998U/ml. Through artificial mutation with UV, the results show that irradiated with UV after 30s, the strain death rate was 92% , at this time strain had higher positive mutation rate, mutation had better results. The enzyme activity after mutation at pH 6 was 3398 U/ml, increased 249%; at pH 8 was 2406U/ml, increased 21%. Passaged five times, the results showed that the enzyme activity produced by the strain had little change and good stability.Constructed phylogenetic tree by colony and cell characterization, 16S rRNA sequence analysis, showed the strain was Flavobacterium. The molecular weight of the protease was 25000Da which determined by SDS-PAGE.Through this study, a Flavobacterium strain obtained from soil, the protease activity of this strain increased nearly three-fold through artificial mutation. This protease had better thermal stability and higher protease activity, adapted to a wide range of pH. This strain can served as a high yield protease producing strain used in fodder, detergent and other industrial production.